1. Field of the Invention
The present invention relates to a photosensitive resin composition used in the production of semiconductors, magnetic bubbling elements and parts for an apparatus of applied optics. It also relates to a process for forming a photo-resist pattern using the photosensitive resin composition described above.
2. Prior Art
In the production of LSI elements, it has been recommended to use double layer photo-resist systems in order to form a highly accurate pattern having a high aspect ratio (i.e. the value obtained by dividing the thickness of resist layer by the width of pattern). Such recommendations or proposals were made by, for example, "MICROCIRCUIT ENGINEERING 81", Sept., 28-30, 1981, Switzerland, and "Provisional Program", No. 386, "Double Layer Resist Systems for High Resolution Lithography", IBM, Thomas J., Watson Research Center, Yorktown Heights, New York, 10598. In the double layer resist systems, a thin top resist layer is applied over a bottom resist layer made of an organic polymer material, and a pattern is initially formed on the top resist layer. Then, the bottom resist layer is etched by reactive ion etchig under oxygen gas (hereafter referred to as O.sub.2 RIE resistance), while using the pattern formed on the top resist layer as a mask, to form a double layer resist pattern. The top resist layer used in such a system must be excellent in durability or excellent O.sub.2 RIE resistance, and must have a high sensitivity and high resolution power.
To meet the aforementioned requirements, photo-resist materials including silicon-containing polymers, which are excellent in durability in O.sub.2 RIE resistance, introduced with high photosensitive groups were regarded as favorable materials. However, the known polysiloxane photo-resist materials having low molecular weights and glass transition temperatures lower than the room temperature are liquid and thus pose difficult handling problems when used to form photo-resist layers. An additional disadvantage of this class of photo-resist materials is low sensitivity to high energy rays. On the other hand, the known polysiloxane photo-resist materials having high molecular weights are rubber-like substances and tend to swell in developer solvents to deform patterns, resulting in deterioration of resolution characteristics. It has been found difficult to form a pattern of high resolution by the use of a double layer photo-resist in which a high molecular weight polysiloxane resist is used in the top layer.
A negative electron-beam resist material for electron beam irradiation process prepared from polydiphenylsiloxane by introducing negative chloromethyl groups in the benzene rings of polydiphenylsiloxane as the main chain through chloromethylation, was reported at the 127th Meeting of American Chemical society (Apr. 8 to 13 day (1984), St. Louis) under the title of "Preparation and Resolution Characteristics of a Novel Silicon Based Negative Resist". The negative resist for electron beam irradiation has a high sensitivity and excellent resistance to reactive ion etching under oxygen gas (O.sub.2 RIE).
However, this resist is not so sensitive to ultraviolet (UV) light which is the type of light widely used for VLSI production because of its high through-put.